Steam turbines are well known. Steam turbines may have closed and sealed containment of the working fluid wherein the working fluid may be water or another fluid. It is also well known to use heat rejected by the steam turbine as a source of heat.
Large trucks perform a large and increasing fraction of the transportation of goods. Many of these trucks have cabins containing appliances requiring substantial amounts of electricity. These include air conditioners, ovens, lamps, electric blankets, etc. Virtually any small appliance sold for use in a home may be found in the cabin of a truck. It is common for the engines of these trucks to be operated constantly while the trucks are parked overnight to generate electricity for these appliances and, when the outside temperature is low, to keep the engine warm. Operating the engine overnight is both wasteful of fuel and a cause of engine wear. An electricity generator independent of the engine is desired to provide the required electricity and also provide heat for warming the engine and the cabin. However, no known electricity generator has achieved market acceptance.
A gas turbine powered electricity generator is known. It offers the desirable qualities of operation on diesel fuel, long life, quiet operation and low pollution and it provides waste heat for heating the engine and the cabin. It has the disadvantages of high cost and high fuel consumption.
Diesel powered generator sets are available at an acceptable price and size. However, they are noisy, generate odorous and unclean exhaust and they are complex devices that require maintenance and are not inexpensive to service.
Rankine cycles for power generation have been known for many years. For many years most electricity has been generated by steam turbines using steam from coal or oil fired boilers or from atomic reactors. It is also well known to use steam turbines for bottoming cycles for large diesel engines to convert waste heat to electricity. In small sizes such as one to five kilowatts steam turbines do not convert the energy in the steam efficiently to power. One reason for poor efficiency in small sizes is that very small turbine entry areas do not provide optimum flow conditions.
Heretofore it has not been recognized that a low pressure closed Rankine cycle turbine is superior to other known ways of providing heat and electricity to the cabin of a truck. Higher efficiency can be achieved by using a working fluid offering lower vapor pressure and lower speed of sound than water vapor. All of the desired features are obtained including operation on diesel fuel, low noise, acceptable exhaust constituents, simplicity, freedom from maintenance and acceptable efficiency.